4 . IMPLEMENTATION DETAILS
In the previous section, we enunciated the special features
that differentiate our system from SDR platforms available in
the market. In this section, we discuss some of the implementation details that characterize and support our choices in the
architecture of the system.
Processor Selection
Our system is mostly FPGA driven with the root processor providing register configuration, connectivity between
modules, host-root connectivity, and data logging. For this
purpose, we do not need full fledged embedded processors
running operating system kernels and device drivers. Our
choices were based on free availability and licensing of the
source, resource usage in FPGA, maturity and availability
of software toolchain. Vendor specific solutions were automatically not considered because of the re-engineering effort
required to build another processor for another FPGA. Only
freely available processors with liberal code licensing were
considered because our platform requires us to modify these
processors to suit our purposes.
Plasma by Steve Rhodes— A simple two or three stage
pipeline processor created by Steve Rhodes in opencores.org
released in the Public Domain [5]. It is coded in VHDL
and consumes very little FPGA resources. It has been used
by researchers in [6] [7] for self-testing processor cores. A
full MIPS toolchain is provided along with a small real time
operating system (RTOS). Sample code for running a web